I've had the same upgrade path, had the HD700, then the T1 and now the HD800. Honestly there's no need to have the HD700 anymore after having both T1 and HD800, and I sold it recently. T1 still sounds better with EDM genre and definitely more exciting and engaging, and has more tighter bass and more impact as well. However, I do agree that overall the HD800 may be a better overall headphone, and sounds absolutely superb with any intrumentals. In fact it changed my taste in music, as it leans more towards Chillstep/ambience EDM than what I've listened to before which is more house and dance. I'm not sure why people say both headphones are similar, to my experience that sound drastically different. It also respond to changes upstream better than the T1, as I notice more of a change going from my STX II to the m9XX using the HD800 than the T1. Honestly I am extremely impressed with the m9XX and think it's practically built for the HD800, and all these talks about not having enough amp juice to power definitely don't apply to the HD800 as I use only 70-72 volume on it (and I believe the control is decibel based). I don't agree that the HD800 is worth more than $300 than the T1 though, as I think the T1 is still a very capable phone and has a more "realistic" soundstage and better imaging than the HD800, tighter and more bass impact, more liquid and organic texture to the sound, more involving and emotional as well. I do agree with the general consensus that the HD800 can sound a bit too clinical, but the overall presentation as a whole package is more appealing. At this point I'm not ready to let my T1 go yet, maybe at a point where I find myself consistently reaching for the HD800.